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LINQ: When to use SingleOrDefault vs. FirstOrDefault() with filtering criteria
... When I ran a SingleOrDefault through LinqPad and VS, I never got SELECT TOP 2, with FirstOrDefault I was able to get SELECT TOP 1, but as far as I can tell you do not get SELECT TOP 2.
– Jamie R Rytlewski
Dec 22 '11 at 15:04
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Select a Dictionary with LINQ
I have used the "select" keyword and extension method to return an IEnumerable<T> with LINQ, but I have a need to return a generic Dictionary<T1, T2> and can't figure it out. The example I learned this from used something in a form similar to the following:
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psql - save results of command to a file
...peruser privileges and will write to a file on the server.
Example: COPY (SELECT foo, bar FROM baz) TO '/tmp/query.csv' (format csv, delimiter ';')
Creates a CSV file with ';' as the field separator.
As always, see the documentation for details
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How to style the with only CSS?
How can I style <option> s of a <select> element with cross-browser compatibility? I know many JavaScript ways which customize the dropdown to convert into <li> , which I'm not asking about.
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How do you do a limit query in JPQL or HQL?
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// SQL: SELECT * FROM table LIMIT start, maxRows;
Query q = session.createQuery("FROM table");
q.setFirstResult(start);
q.setMaxResults(maxRows);
share
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Xcode 6 Storyboard the wrong size?
...way at some point."
You probably haven't added the layout constraints.
Select your label, tap the layout constraints button on the bottom:
On that menu add width and height (it should NOT be the same as mine) by checking their checkbox and click add constraints. Then Control-drag your label t...
How can I create a copy of an Oracle table without copying the data?
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Just use a where clause that won't select any rows:
create table xyz_new as select * from xyz where 1=0;
Limitations
The following things will not be copied to the new table:
sequences
triggers
indexes
some constraints may not be copied
materialized view...
python-pandas and databases like mysql
...a_conn = cx_Oracle.connect('your_connection_string')
df_ora = pd.read_sql('select * from user_objects', con=ora_conn)
print 'loaded dataframe from Oracle. # Records: ', len(df_ora)
ora_conn.close()
And here is the equivalent example for MySQLdb:
import MySQLdb
mysql_cn= MySQLdb.connect(host='...
Invalid postback or callback argument. Event validation is enabled using '
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I had an experience with DataGrid. One of it's columns was "Select" button. When I was clicking "Select" button of any row I had received this error message:
"Invalid postback or callback argument. Event validation is enabled using in configuration or
<%@ Page EnableEve...
varbinary to string on SQL Server
...AST it
declare @b varbinary(max)
set @b = 0x5468697320697320612074657374
select cast(@b as varchar(max)) /*Returns "This is a test"*/
This is the equivalent of using CONVERT with a style parameter of 0.
CONVERT(varchar(max), @b, 0)
Other style parameters are available with CONVERT for differ...